Two of the three groups vying to bring a baseball franchise to Washington have joined forces and, suddenly, what once was a complex maze of names now appears to be reduced to a situation in which Jack Kent Cooke is on one side of the equation and everyone else on the other.

Sources said yesterday that Dr. Robert Schattner and developer Ted Lerner, who have been linked to baseball interests in the District of Columbia for a decade, will now be working with a potential ownership group consisting of land developers Oliver T. Carr Jr., James Clark and Robert Smith.

Former baseball commissioner Bowie Kuhn is serving as spokesman for this group and is expected to take on some front office role should this group get an expansion franchise, possibly as soon as 1987.

Cooke, who owns the Redskins, was the first to say he wanted to bring a baseball team here, and has made it clear that he would like to own it himself.

Sources indicated there have been efforts to unite Cooke with the remaining group. He was unavailable for comment.

Commissioner Peter Ueberroth and baseball's Long Range Planning Committee will hold a screening session for 12 cities hoping for expansion teams Nov. 7-8 in New York. Although no definitive decision is expected on expansion then, it's likely to be clearer as to which cities are considered best qualified.

There is also the possibility that a group could buy an existing franchise and move it here. The San Francisco Giants are for sale, Ueberroth has said the franchise might need to move and Cooke is known to have contacted Giants owner Bob Lurie.